JPH0517676A - Slippery polyester resin composition - Google Patents

Abstract

PURPOSE:To provide the subject composition free from phase separation and having good sliding characteristics. CONSTITUTION:This composition consists of 50-99wt.% polyester resin (a) and 0.5-40wt.% polyester/polyolefin block copolymer (b) dispersed in component (a) as particles with a diameter of 3mum or smaller. This composition is free from phase separation and reveals enhanced sliding characteristics. Therefore, it is useful for use as sliding members of various parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slidable polyester resin composition having good sliding characteristics without phase separation.

[0002]

2. Description of the Related Art Thermoplastic resins such as polyacetal, polyamide, polyester and polycarbonate, which have been conventionally used for mechanical parts such as bearing parts and gear parts, are made of fluororesin and ultra high molecular weight compounds in order to improve friction and wear characteristics. Polyethylene, molybdenum disulfide, graphite, mineral oil, etc. are mixed.

However, since fluororesin is an expensive material, compounding it causes the cost of the entire composition to be high, and molybdenum disulfide and graphite have the disadvantage that the effect is not sufficient. Further, the heat resistance of mineral oil is insufficient, causing a problem in moldability. Japanese Patent Publication 4
6-41456 and the like propose mixing powdery ultrahigh molecular weight polyethylene, but it is usually difficult to uniformly disperse the ultrahigh molecular weight polyethylene in a thermoplastic resin because of its high viscosity. Moldability and mechanical properties deteriorate. When low-viscosity polyethylene is blended, there is a problem that phase separation occurs during molding.

[0004]

As described above, in the range of the prior art, it was difficult to obtain a slidable material having no phase separation and excellent slidability and moldability. An object of the present invention is to provide a slidable polyester resin composition that does not have the above problems.

[0005]

The present inventors have found that the above problems can be solved by dispersing a polyester resin-polyolefin block copolymer in a polyester resin, and completed the present invention. Came to let me. That is, the present invention relates to (a) polyester resin 50 to 9
9 wt% and (b) polyester resin-polyolefin block copolymer 0.5 to 40 wt%,
The present invention provides a polyester resin composition in which the component (a) forms a continuous phase and the component (b) forms a dispersed phase, and the dispersed phase has a dispersed particle size of 3 μm or less.

The polyester resin used as the component (a) in the present invention may be a known polyester which is usually used in injection molding, extrusion molding and the like.
It is a polymer having a COO-bond and can be melted by heating. Among these, a polymer having a carbonic acid ester bond in the molecular main chain is also included. Specific examples thereof include a dicarboxylic acid component containing terephthalic acid as a main component and a diol component. As the dicarboxylic acid component, other than terephthalic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid or the like having 2 to 20 carbon atoms can be used. Aromatic dicarboxylic acids, isophthalic acid, aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid may be used alone or as a mixture. The diol component may be ethylene glycol, propylene glycol, tetramethylene glycol. , Aliphatic glycols such as hexamethylene glycol, 1,4-
Alicyclic diols such as cyclohexanediol, xylylene glycol, 2,2-bis (4-hydroxyphenyl) propane, 2,2- (4-hydroxy-3,5-dibromophenyl) propane, 2,2- (4 Specific examples thereof include aromatic diols such as -hydroxyethoxyphenyl) propane and 2,2- (4-hydroxyethoxy-3,5-dibromophenyl) propane, and mixtures thereof.

A small amount of a polybasic acid such as trimellitic acid as the carboxylic acid component or a polyhydric alcohol such as glycerin as the diol component may be used. Among these, particularly preferable polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyarylate. The above polyester resin is a phenol / tetrachloroethane mixed solution (6
/ 4 weight ratio), the intrinsic viscosity measured at 30 ° C. is preferably 0.4 or more, and more preferably 0.5 or more.

Specific examples of the polymer having a carbonic acid ester bond in the molecular main chain include a carbonic acid ester of a dihydroxydiaryl compound, and a typical example thereof is 2,2-bis (4-hydroxyphenyl). An example is polycarbonate produced from propane. Examples of the dihydroxydiaryl compound include 2,2-bis (4-hydroxyphenyl) propane, bis (hydroxyaryl) alkanes, bis (hydroxyaryl) cycloalkanes, dihydroxydiarylethers, dihydroxydiarylsulfides, and dihydroxy. Examples thereof include diaryl sulfones.

These may be used alone or in admixture of two or more, but in addition to these, hydroquinone, resorcin, 4,4'-dihydroxydiphenyl and the like may be mixed and used. You may use the said polyester resin in mixture of 2 or more types. In the present invention, the polyester resin-polyolefin block copolymer used as the component (b) is obtained by reacting a polyester resin with a polar group-containing polyolefin resin. The amount of the copolymer obtained is insoluble after the copolymer is heated and dissolved in a phenol / tetrachloroethane mixed solution (6/4 weight ratio), the insoluble matter is centrifuged, and the insoluble matter is Soxhlet-extracted with hot xylene. Can be measured as the residual amount of The component (b) can be produced by reacting a polyester resin and a polar group-containing polyolefin resin by an arbitrary method.

The component (b) in the present invention is considered to be one in which the respective blocks of the polyester resin and the polyolefin resin as the component (a) are chemically bonded, but the chemical structure etc. are not clear. .. The polar group-containing polyolefin resin referred to in the present invention means at least one polar group selected from the group consisting of a carboxyl group and its derivative group, a hydroxyl group, an epoxy group, an amino group, a nitrile group, an amide group, and -SO2 group. Having a carboxylic acid group or a metal base thereof, a polyolefin having a glycidyl group, an acrylic acid and its derivative residue or a methacrylic acid and its derivative residue, a maleic anhydride, etc. Polyolefins having an acid anhydride residue of, and the like are included.

Examples of the polar group-containing polyolefin resin include ethylene-glycidyl methacrylate copolymer,
Α-Olefin copolymers such as ethylene-vinyl acetate glycidyl methacrylate copolymer, ethylene-carbon monoxide-glycidyl methacrylate copolymer, ethylene-maleic anhydride-methyl methacrylate copolymer, ethylene-acrylic acid copolymer , Α, β-unsaturated carboxylic acid derivative-grafted polyolefins obtained by graft-polymerizing an α, β-unsaturated carboxylic acid derivative in the presence or absence of a peroxide in a polyolefin, Proc.
Examples include a graft copolymer produced by the method described in Vol. 2, No. 2, p89-95.

As the third component, a polyfunctional reactive compound such as a polyfunctional epoxy compound or polyisocyanate can be added to the component (b). This makes it possible to bond the polyester resin and the polar group-containing polyolefin resin to form a polyester resin-polyolefin block copolymer. Preferred polyfunctional reactive compounds include diepoxy compounds such as epoxy resins, diphenylmethane diisocyanate, diisocyanates such as hexamethylene diisocyanate.

In the present invention, the component (c) may contain 0 to 40 wt% of a polyolefin resin. Here, the component (c) is ethylene, propylene, butene-1,
A polymer of α-olefin such as 4-methylpentene-1, isobutylene or a copolymer containing at least 65 wt% of these α-olefins. For example, high and medium and low pressure polyethylene, ethylene and vinyl acetate copolymer,
Examples thereof include copolymers of ethylene and acrylic acid, methyl acrylate and the like, polypropylene, ethylene and propylene copolymers, poly-4-methylpentene-1, polyisobutylene and the like.

In the present invention, the component (b) forms a dispersed phase in the continuous phase of the component (a). In the composition containing the component (c), the components (b) and (c) form a dispersed phase in the continuous phase of the component (a). The dispersed particle size of the dispersed phase is
It must be 3 μm or less, preferably 2 μm
Or less, and more preferably 1 μm or less. The compounding ratio of the component (a) in the present invention is in the range of 50 to 99 wt%. When the component (a) is less than 50 wt%, (a)
It becomes difficult for the components to form a continuous phase, and mechanical strength and the like decrease. If it exceeds 99 wt%, the effect of imparting sliding characteristics becomes small. Preferably, it is in the range of 60 to 97 wt%.

The blending ratio of the component (b) in the present invention is
It is within the range of 0.5 to 40 wt%. If it is less than 0.5 wt%, the effect of improving the sliding property is small, and if it exceeds 40 wt%, the mechanical strength is lowered. Preferably 1 to 30 wt
%. The blending ratio of the component (c) in the present invention is 0.
It is in the range of ˜40 wt%. If it exceeds 40 wt%, the mechanical properties will deteriorate.

The method for producing the resin composition of the present invention includes:
(1) First, a polyester resin-polyolefin block copolymer of the component (b) is produced, and then a polyester resin of the component (a) and, if necessary, a polyolefin resin of the component (c) are added, By sufficiently melt-kneading, (2) by adding the polyester resin as the component (a), the polar group-containing polyolefin resin, and if necessary, the polyolefin resin as the component (c), and thoroughly kneading at once. There are methods for producing the composition, and any method may be used. If the kneading is not sufficient, the component (b) or the component (c) will not be dispersed in the component (a) with a dispersed particle diameter of 3 μm or less.

The polyester resin-polyolefin block copolymer as the component (b) is prepared by adding a polyester resin and a polar group-containing polyolefin resin, and if necessary a binder such as polyisocyanate or diepoxy compound, It can be obtained by melt-kneading. An example of the melt-kneading method is a method of melt-kneading using an extruder or the like, but in order to sufficiently react the polyester-based resin and the polar group-containing polyolefin-based resin to produce a polyester-based resin-polyolefin block copolymer It is preferable to have sufficient kneading ability and residence time. A preferable kneading device is a twin-screw or more multi-screw extruder capable of incorporating a kneading block at any position of a screw. The kneading block part is preferably 5% of the whole screw.
As described above, a structure that occupies 10% or more is more preferable. The kneading temperature may be higher than the melting point of the polyester resin or higher than the glass transition point, but is preferably 22.
It is good to carry out in the range of 0 ° C to 350 ° C, more preferably 230 ° C to 320 ° C.

The residence time in the kneading device is preferably in the range of 10 seconds to 1 hour, more preferably 15 seconds or more and 30 minutes. The resin composition of the present invention is a known inorganic or organic filler or reinforcing agent (glass fiber, carbon fiber, whiskers, mica, talc) in addition to the above components as long as the characteristic slidability is not impaired. , Calcium carbonate, potassium titanate, wollastonite, etc.), flame retardants, flame retardant aids, antioxidants, stabilizers (transesterification inhibitors, etc.), UV absorbers, plasticizers, antistatic agents, various colorants Further, additives such as a lubricant, a releasing agent, a nucleating agent and the like can be added and used.

The method for molding the resin composition of the present invention is not particularly limited as long as it is a commonly used molding method such as injection molding, extrusion molding, compression molding and blow molding, and the shape of the obtained molded article is not limited. However, it is not restricted by the molding method.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Various measurements in Examples and Comparative Examples were performed according to the following methods. (1) Measurement of block copolymer content The obtained pellets were dissolved by heating with a phenol / tetrachloroethane mixed solution (6/4 weight ratio), the insoluble matter was centrifuged, and the insoluble matter was further heated with hot xylene. The value of the insoluble residue after Soxhlet extraction was expressed in% by weight was determined as the block copolymer content. (2) Measurement of dispersed particle size Dumbbells based on ASTM D-638 are injection molded,
The molded piece was cut near the center and stained with osmic acid, and then observed with a transmission electron microscope from the flow direction. The dispersed particle diameter was obtained as a volume average diameter of circle equivalent diameter by an image analyzer (IP-1000, manufactured by Asahi Kasei Kogyo KK).

(3) Phase Releasability A tensile test of an injection-molded piece was carried out in accordance with ASTM D-638, and the fracture surface of the sample after the test was visually observed and judged. The case where no phase separation was observed was indicated by ◯, the case where a slight phase separation was observed was indicated by Δ, and the case where the phase separation was severely unusable for practical use was indicated by x. (4) Sliding characteristics After drying the obtained pellets with a hot air dryer at 135 ° C for 6 hours, the outer diameter of the pellets according to JIS-K7218- (A) was 25.
6 mm x inner diameter 20 mm x height 15 mm, contact area 2 cm
² cylindrical sample injection molding machine (auto shot 15A;
It was molded using FANUC Co., Ltd. Atmospheric temperature 2 using a thrust type friction tester (manufactured by Toyo Seiki Seisakusho)
At 3 ° C, non-lubricated, select your own material as a friction partner, keep the surface pressure at the time of measurement constant at ² kg / cm ² respectively, run continuously at a sliding linear velocity of 6 cm / sec for a total running distance of 50 km, and mold. The amount of wear per unit distance of the product was obtained.

[0022]

Reference Example 1 Production of Polyester Resin-Polyolefin Block Copolymer (PC-PO) Of the components shown in Table 1, 100 parts of PC2 and PO1
After dry blending 100 parts and 1 part of MDI, using a co-rotating twin-screw kneading extruder (ZSK-25; W & P Co., caliber 25 mmφ, L / D = 42), the kneading block was 8% of the whole. With such a screw configuration,
At a set temperature of 240 ° C and a screw rotation speed of 250 rpm,
The mixture was melted and kneaded to obtain a pellet-shaped polyester resin-polyolefin block copolymer. The block copolymer content of the product was 78 wt%.

[0023]

Reference Example 2 Production of Polyester Resin-Polyolefin Block Copolymer (PBT-PO) Of the components shown in Table 1, 100 parts of PBT, PO1
After 100 parts of MDI and 1 part of MDI were dry-blended, melt kneading was carried out in the same manner as in Reference Example 1 except that the set temperature was 250 ° C. to obtain a pellet-shaped polyester resin-polyolefin block copolymer. The block copolymer content of the product was 84 wt%.

[0024]

Examples 1 and 2 Using the polyester resin-polyolefin block copolymer produced in Reference Example 1, the components shown in Table 1 were dry blended at the compounding ratio shown in Table 2,
Using a co-rotating twin-screw kneading extruder (ZSK-25; manufactured by W & P Co., caliber 25 mmφ, L / D = 42), the kneading block was set to 260 ° C. with a screw configuration such that the kneading block was 10% of the whole. And melt-kneaded to obtain a pelletized composition. The obtained pellets were molded and the physical properties were measured. The results are shown in Table 2. The composition of the present invention did not cause phase separation, was excellent in sliding characteristics, and had good moldability.

[0025]

[Example 3] The components shown in Table 1 were dry blended at the compounding ratios shown in Table 2, and then a co-rotating twin-screw kneading extruder (ZSK-25; manufactured by W & P, diameter 25 mmφ, L / D) was used.
= 42), the kneading block is the entire 15
% And melt-kneaded at a preset temperature of 260 ° C. to obtain a pellet-shaped composition containing a polyester resin-polyolefin block copolymer.

The obtained pellets were molded and the physical properties were measured. The results are shown in Table 2. The composition of the present invention did not cause phase separation, was excellent in sliding characteristics, and had good moldability.

[0027]

Example 4 Polyester resin produced in Reference Example 2
Using the polyolefin block copolymer, the components shown in Table 1 were melt-kneaded at the compounding ratios shown in Table 2 in the same manner as in Examples 1 and 2, and evaluated. As shown in Table 2, the composition of the present invention had no phase separation, excellent sliding characteristics, excellent sliding characteristics, and good moldability.

[0028]

Comparative Example 1 A composition having the compounding ratio shown in Table 2 was produced.
The results of molding and measuring the physical properties are shown in Table 2.

[0029]

[Comparative Example 2] After dry blending with the same composition ratio as in Example 3, a single screw extruder (diameter 40 mmφ, L / D = 3)
0, Tanabe Plastic Co., Ltd., set temperature 26
The mixture was melt-kneaded at 0 ° C. to obtain a pelletized composition. In this kneading method, the block copolymer was not sufficiently formed, and the sample had a block copolymer content of 0.4% and a dispersed particle size of 3.5 μm.

[0030]

Comparative Example 3 A composition having the compounding ratio shown in Table 2 was produced.
The results of molding and measuring the physical properties are shown in Table 2.

[0031]

[Comparative Examples 4 and 5] The sliding characteristics of molded articles made of polycarbonate alone and polybutylene terephthalate alone were measured, and the results are shown in Table 2.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

The resin composition of the present invention thus obtained exhibits high sliding characteristics without phase separation,
It can be used as a sliding member for various parts. As these various parts, for example, gears, cams, guide rails,
Carriage, switch parts, bushings, bearings,
It can be suitably used as a structural material and a mechanical material such as a sleeve, a slip cylinder, a key top and a key base, and can be applied as a sliding member for various parts other than those described here. As a method of applying these, the molded body can be used as it is in a block shape, a film shape, a sheet shape, or the like, or can be used in combination with one or more other resin materials by multicolor molding.

Claims (1)

Claims: (a) Polyester resin 50 to 99 wt.
%, And (b) polyester resin-polyolefin block copolymer 0.5 to 40 wt%, (a)
A slidable polyester resin composition, wherein the components are a continuous phase, the component (b) forms a dispersed phase, and the dispersed phase has a dispersed particle diameter of 3 μm or less.